I have been chasing a driveline vibration in my 61 since I have owned the car. At one point, it seemd to have almost dissapeared. I had the car serviced a few weeks ago, including adding transmission lube. They did not lube the front u joint. The vibration reappeared and was pretty bad. It has tapered off a bit. Today I pulled the driveshaft, suspicious of the front u joint or perhaps the driveshaft itself. The front(and rear) joints were free with no signs of play. The balance weight was present on the driveshaft. I lubed the front joint, and it was not dry, despite probably not having been lubed since Carter was in office. The thing I did find which concerned me was that the transmission output shaft had a bit of play in it. Side to side. Not much, but I wouldnt think it would have any. I test drove the dar and the vibration kicked in about 30 MPH but it dissapeared at about 40. Does not seem to be related to coast/power/backing down conditions. Only speed. Is not engine related, as I can push in the clutch at speed without any change in the vibration. Any advise would be appreciated.
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Re: C1 driveline vibration
Sounds like your front yoke and tailshaft bushing are worn, giving the radial play you mentioned. Certainly worth your while to pull them apart again for a look see.
Would you say that the vibration is at a higher frequncy than an out-of-balance wheel? If so, then it's probably in the driveshaft area.
Mike
Quebec NCRS Chapter -
Re: C1 driveline vibration
in addition to Mike's comments, which I echo, check the bearing in the retainer at the back of the case, right in front of the reverse gear. If the bearing is loose in the retiner, or has excessive slop, it should be replaced also. Probably a good thing to do anyway in light of having the thing apart to follow mikes path. Another trick is to shim the crossmember to frame location downword about 3/16 of an inch with a shim. that changes the driveshaft angle slightly and can make a world of difference I'm told. (I can't wail to try it on my '62 this spring.Comment
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Re: C1 driveline vibration
To add to what Clup has said...I have many Street Rod buddies, and one of their topics of discussion is the angle of the driveshaft...the angle that it comes out of the trans, and the angle that it goes into the differential. If those angles are not correct, driveline vibration ensues. I have no personal knowledge in this area....just repeating what I've heard many many times. Ask a few Street Rod builders. They might point you in the right direction as to the proper angles, or a reference book to check on your own. As Clup has said, shimming the trans mount up or down would be the easiest thing to try in my opinion. Changing the angle of the rear end would be more difficult. Chuck1963 Corvette Conv. 327/360 NCRS Top Flight
2006 Corvette Conv. Velocity Yellow NCRS Top Flight
1956 Chevy Sedan. 350/4 Speed Hot RodComment
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Re: C1 driveline vibration
Ed, when I got (rescued) my '57, it had no shims between the trans crossmember and the frame; when I completed the restoration two years later and drove it for the first time, it had a driveline vibration AND the front universal was lightly scraping the bottom of the tunnel. I loosened up the 4 crossmember bolts and shimmed it down 1/4" at all 4 points, and both the scraping and the driveline vibration disappeared - been fine ever since. Typically, factory-installed shims are the first thing that disappears from old Corvettes early in their lives, and some Kentucky windage is required to re-establish correct relationships between components. Good Luck.
JohnComment
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Re: C1 driveline vibration
If memory serves me correct driveline vibration was a serious problem prior to 59 when the pinion angle was changed.I belive that Chevrolet made angle shims to correct the problem on earlier year cars or cars which had been raised in the rear to clear larger tires.Comment
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Re: C1 driveline vibration
Well, I haven't looked but I'd bet a moon pie and a yeller dope (orange drink to you non-southerners) that my car has NO shims. I don't know for sure, but I have a suspicion that the car was originally an automatic, due to an unused relay I found on the firewall that I'm told was susposed to be for an auto. Since it is a whole lot easier to shim the transmission support down a bit than it is to pull the trans, I guess I'll start there. I have my fingers crossed on this one. I'll let you know in a few days. Thanks to all for the info.Comment
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Re: C1 driveline vibration
John, Before I started taking the trans out and apart, I would check to make sure the driveshaft is straight and rotating straight. Put the car on jackstands, supported by the axle and rotate the driveshaft with a piece of chalk [mounted on something to give it support] to determine if in fact the driveshaft is true. Don't start getting into big things until you have investigated all of the easy checks.Comment
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Re: C1 driveline vibration
Ed,
I once chased a driveline vibration (non-Corvette) for some time and didn't find the source until I got the vehicle up in the air and running in gear and could look at the drive shaft and rear end while everything was rotating.
You might consider getting the car up on jack stands and look underneath while everything is turning.
Good Luck.
Terry
TerryComment
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Re: C1 driveline vibration
Ed
An easy check for pinion & tranny angles is a bubble protracter for constructon workers check both the tranny & rear , they should be the same . Of course all of thee other checks apply , worn parts is worn parts Jeff- new vette owner , old hot rodderComment
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